Steerable medical device

ABSTRACT

A medical device is provided. The medical device includes an elongated device body having a steerable portion including a plurality of segments. The segments are co-axially mounted over at least one elongated elastic element which is configured for limiting rotation of the segments with respect to each other. The medical device also includes a control wire running alongside the elongated device body and being unrestrained at the steerable portion such that tensioning of the control wire angles the steerable portion from a longitudinal axis of the elongated device body and deflects the control wire away from the steerable portion.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a steerable medical device and, moreparticularly, to a medical device which includes unrestrained controlwires capable of deflecting away from the steerable portion of themedical device when tensioned.

Medical devices such as endoscopes and catheters are widely used inminimally invasive surgery for viewing or treating organs, cavities,passageways, and tissues. Generally, such devices include an elongateddevice body which is designed for delivering and positioning adistally-mounted instrument (e.g. scalpel, grasper or camera/cameralens) within a body cavity, vessel or tissue.

Since such devices are delivered though a delivery port which ispositioned through a small incision made in the tissue wall (e.g.abdominal wall), and are utilized in an anatomically constrained space,it is desirable that the medical device or at least a portion thereof besteerable, or maneuverable inside the body using controls positionedoutside the body (at the proximal end of the medical device). Suchsteering enables an operator to guide the device within the body andaccurately position the distally-mounted instrument at an anatomicallandmark.

In order to control deflection of a steerable portion of the device andthus steer the instrument mounted thereon, steerable medical devicestypically employ one or more control wires which run the length of thedevice and terminate at the distal end of the steerable portion or atthe distal tip.

The proximal end of each control wire is connected to the user operatedhandle; pulling of the wire bends the device body and deflects thesteerable portion with relation the pulled wire.

Numerous examples of steerable devices are known in the art, see forexample, U.S. Pat. Nos. 2,498,692; 4,753,223; 6,126,649; 5,873,842;7,481,793; 6,817,974; 7,682,307 and U.S. Patent Application PublicationNo. 20090259141.

Although prior art devices can be effectively steered inside the body,the relatively small diameter of the elongated device body (which isdictated by the diameter of the delivery port), severely limitsangle-of-deflection capabilities and increases the pull force requiredto deflect the steerable device portion.

As such, it would be highly advantageous to have a steerable medicaldevice having a device body narrow enough for delivery through standarddelivery ports and yet capable of providing wide angle steering of thedeflectable portion within the body while minimizing the pull forcerequired for such steering.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is providedmedical device comprising: (a) an elongated device body having asteerable portion including a plurality of segments; (b) optionally, atleast one elongated elastic element running through the plurality ofsegments and being configured for limiting rotation of the segments withrespect to each other; and (c) at least one control wire runningalongside the elongated device body and being unrestrained at thesteerable portion such that tensioning of the at least one control wireangles the steerable portion from a longitudinal axis of the elongateddevice body and deflects the at least one control wire away from thesteerable portion.

According to further features in preferred embodiments of the inventiondescribed below, each of the plurality of segments is configured so asto limit rotation thereof with respect to flanking segments.

According to still further features in the described preferredembodiments the at least one elongated elastic element has a rectangularcross section.

According to still further features in the described preferredembodiments the medical further comprises an elastic tubular sheathcovering the steerable portion.

According to still further features in the described preferredembodiments the medical device comprises a plurality of control wires,each being for angling the steerable portion of the elongated devicebody in a specific direction.

According to still further features in the described preferredembodiments the plurality of segments are interlinked.

According to still further features in the described preferredembodiments the medical device further comprises a tissue manipulatorattached to a distal end of the elongated device body.

According to still further features in the described preferredembodiments the tissue manipulator is a grasper, a tissue cutter, or aneedle holder.

According to still further features in the described preferredembodiments the medical device further comprises a rigid sheath coveringnon-steerable portion of the elongated device body.

According to still further features in the described preferredembodiments the elongated elastic element is a spring coil.

According to still further features in the described preferredembodiments rotation between adjacent segments of the plurality ofsegments is limited by tab-slot engagement between the adjacentsegments.

According to still further features in the described preferredembodiments the control wire is trapped between the device body and therigid sheath at the non-steerable portion.

According to still further features in the described preferredembodiments the medical device further comprises at least oneretractable lever positioned at a distal end of the steerable portion,the at least one retractable lever being attached to a distal end of theat least one control wire.

According to another aspect of the present invention there is provided amedical device comprising: (a) an elongated device body having asteerable portion including an elastic shaft; and (b) at least onecontrol wire running alongside the elongated device body and beingunrestrained at the steerable portion such that tensioning of the atleast one control wire angles the steerable portion from a longitudinalaxis of the elongated device body and deflects the at least one controlwire away from the steerable portion.

According to still further features in the described preferredembodiments the at least one control wire is routed through a pair ofguide clamps flanking the steerable portion.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing a steerable medical devicehaving a deflectable region being configured capable of angling morethan 180 degrees with respect to a longitudinal axis of the device.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIGS. 1a-1h illustrate the present device and the operation of thehandle controlling the deflection of the steerable portion(s) andeffector end.

FIG. 2 illustrates the elongated body (fitted with grasper end) and thedrive unit components of the device of FIG. 1.

FIGS. 3a-b illustrate one embodiment of a steerable potion of thepresent device.

FIGS. 4a-b illustrate another embodiment of a steerable potion of thepresent device.

FIGS. 5a-d illustrate one embodiment of a link utilizable forconstructing a steerable portion of the present device (FIGS. 5a-c ),and a steerable portion constructed from a plurality of links.

FIG. 6 illustrates a steerable portion with several links removedexposing the spring element fitted within a central core of the links.

FIGS. 7a-h illustrate an embodiment of the present device that includesa steerable portion fabricated from interconnected disc-shaped links.FIGS. 7a-c illustrate isometric and side views of the device, whileFIGS. 7d-h illustrate the disc-shaped links.

FIGS. 8a-q illustrate an embodiment of the present device that includestwo offset steerable portions deflectable to form, for example, U-shaped(FIG. 8k ) and S-shaped (FIG. 8l ) articulation configurations.

FIGS. 9a-b illustrate an embodiment of the present device that includesa unitary flexible shaft fitted with guides for routing the controlwires. FIG. 9b illustrates deflection of the shaft between guides.

FIGS. 9c-i illustrate another embodiment of the present device thatincludes a unitary flexible shaft including cutouts for enablingdeflection. FIG. 9i illustrates deflection of the shaft between guides.

FIGS. 9j-k illustrate a unitary flexible shaft (FIG. 9k ) constructedfrom disc-like links (FIG. 9j ) that are pinned together around a singlerotatably-offset pivot point.

FIGS. 10a-c are images of a prototype device tested through variousarticulation states and deflection angles of the steerable portion.

FIGS. 11a-b illustrate a steerable portion composed of transparentlinks.

FIG. 12 is a flowchart diagram describing a design ‘algorithm’ forconstructing an articulating region of predetermined properties usingthe teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a medical device and system which can beused in minimally invasive surgery. Specifically, the present inventioncan be used to provide enhanced steering.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details set forth in the following description or exemplified bythe Examples. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

Steerable medical devices for use in minimally invasive surgery are wellknown in the art. Such devices typically utilize one or more controlwires operable from a proximal end of the device positioned within thebody to deflect and thus steer a distal portion of the device positionedwithin the body. In order to enable the control wire to efficientlydeflect the distal portion of the device, the longitudinal axis of thecontrol wire must be offset from the axis of deflection. In general, thegreater the offset, the greater deflection that can be achieved withless pulling force applied to the control wire.

Since the diameter of minimally invasive devices is dictated by thedelivery port used to gain access to the intrabody tissues (typically 5,8 or 10 mm), in existing tools the offset between the control wire andthe deflection axis is in fact limited by the diameter of the tool'sshaft the diameter of the port and the configuration of the device.

To overcome this limitation, the present inventor has devised a uniquecontrol wire guide configuration which minimizes the overall diameter ofthe device body and yet provides control wire offset when the steerableportion is angled.

Thus, according to one aspect of the present invention there is provideda medical device which includes a steerable intrabody portion capable ofbeing steered through a wide range of angles (up to 180 degrees) andpatterns such as zigzag or varied diameter curves at one or more pointsalong its length.

As used herein, the phrase “medical device” refers to any deviceutilizable in treatment of a subject, preferably a human subject. Themedical device of the present invention is preferably used in minimallyinvasive surgery wherein a steerable distal portion thereof positionedwithin a body of a subject is controlled from a proximal end positionedoutside the body (extra corporeally) via a control mechanism whichpreferably includes control wires. The medical device can be used forviewing or for manipulating tissues within any body cavity. Examples ofmedical devices which can benefit from the present invention include anendoscope (e.g. laparoscope or thorascope), a catheter, a needle holder,grasper, Scissors, hook, stapler, retractor and the like.

The medical device of the present invention includes an elongated devicebody having a distal portion which is steerable within a body of asubject (also referred to herein as steerable portion), preferably viaat least one control wire. As is further described herein, the steerableportion of the device can be deflected in various directions andconfigurations, e.g. the entire steerable portion can be deflected(arced) towards one direction using a single control wire, or a firstsegment of the steerable portion can be deflected in one direction whileanother can be deflected in an opposite direction (zigzag andmulti-plane articulation) using two or more control wires. FIGS. 10a-cof the Examples section which follows provides several examples thedeflection capabilities of the present device.

The elongated device body includes one or more control wires disposedalong its length. The proximal end of the control wire is attached tocontrol levers which are actuatable by a handle of the medical device orby an electro-mechanical mechanism. The distal end of the control wireis attached to the device body (at a point past the steerable portion).The length of the control wire can be routed within or alongside thedevice body with the section of wire corresponding to the steerableportion being routed outside the device body such that it can freelymove out from the longitudinal axis of the device body (offset) when thesteerable portion is angled.

Enabling the control wire to freely move away from the device body atthe steerable portion provides several advantages:

(i) gradually reduces the force needed to deflect the steerable portiononce the steerable portion curves;

(ii) negates the need for wire guides at the steerable portion (anoptionally along the entire device body) thus simplifying constructionand reducing friction on the control wires;

(iii) reduce the friction between the wire and the wire guides;

(iv) allows to use smaller diameter wires because the force needed tosteer the articulation is significantly smaller;

(v) reduces the means of connecting the wire to the distal end of thearticulation because the force needed to steer the articulation issignificantly smaller;

(vi) (iv)+(v) allows to reduce the diameter of the device when linearthus facilitating insertion and removal into body (through, for example,a trocar port);

(vii) when using the tool manually, all the above a allows the surgeonto operate the tool with much less effort;

(viii) makes the use of electro-mechanic actuators possible. As it willbe described later the significant force reducing allows the use of verysmall actuators (such as motors) which enables the design of a lightweight fully motorized device;

(ix) The use of very small actuators (such as motors) enables to operatea fully motorized device with small energy consumption; and

(X) Enabling use of transparent materials in the steerable portion.FIGS. 1-11 b illustrate several embodiments of the present device whichis referred to herein as device 10.

FIG. 1a illustrates a laparoscopic configuration of device 10. Device 10includes an elongated device body 12 (also referred to herein aselongated body 12 or body 12) which includes a steerable portion 14fabricated from a series of segments 16 (shown in FIGS. 5a-c ).

Device body 12 can be 20-40 cm in length and 5-12 mm in diameter. Devicebody 12 can be hollow or solid depending on the use of device 10. Forexample, in cases where device 10 is used to steer an endoscopic camera,device body 12 can be hollow in order to enable routing of wires orfiber optic cables from a user operable end (handle) to a camera or lensmounted on a distal end of elongated device body. A hollow device body12 can also be used to route wires for controlling an operation of atissue manipulator head such as a grasper and/or for accommodating atleast one elongated elastic element for providing device body withelastic rigidity (further described hereinbelow).

Device 10 also includes a user operable interface 18 attached toproximal end of device body 12 and an effector end 20 (e.g. tissuemanipulator such as a grasper) attached to a distal end of device body12. Interface 18 functions in controlling and setting a orientation andposition of elongated body 12, angling of steerable portion 14 and inoperating effector end 20 (e.g. opening/closing, rotating and angling agrasper).

For example, in the configuration shown in Figure la, a user (e.g.surgeon) can press/release handles 300 to close and open the jaws of thegrasper, rotate interface 18 in order to rotate the grasper jaws, and/ortilt housing 400 in order to deflect steerable portion 14. These actionscan be done separately or simultaneously.

An interface 18 that can be used with device 10 is further describedhereinbelow. Alternatively, the device 10 can incorporate the interfacedescribed in U.S. Provisional Patent Application No. 61/694,865, thecontents of which are fully incorporated herein.

FIG. 2 illustrates routing of control wires 22 from drive unit 24 to apoint distal to steerable portion 14. Drive unit 24 can include levers,pulleys and gears for translating hand movements of the user (controlmovements) to pulling of control wires 22. Such transfer can bemechanical (manual) or motorized. A motorized embodiment of drive unit16 is further described in U.S. Provisional Patent Application No.

61/872,727.

In the embodiment shown in FIG. 2, control wires 22 are routed withindevice body 12 (e.g. under a sheath covering device body 12 or in thetube) up to steerable portion 14. At steerable portion 14, control wires22 (one shown) is free from device body 12, such that angulation ofsteerable portion deflects control wire 22 away from the longitudinalaxis of device body 12. Deflection of the control wire away from thelongitudinal axis of the device (radially outward) increases the offsetbetween the control wire and the deflection axis of the elongated devicebody and thus minimizes the pulling force needed to achieve deflection.

Steerable portion 14 (composed of links) is shown in greater detail inFIGS. 3a-4b . In FIGS. 3a-b , control wires 22 ₂ 22 ₃ are attached todevice body 12 at point B and routed into body 12 through point A₂. Inbetween, control wires 22 ₂ 22 ₃ are free to move away from device body12 and thus deflect away from device body 12 when pulled to anglesteerable portion 14. FIG. 3a illustrates pulling of control wires 22 ₂22 ₃, control wire 22 ₁ is not pulled and thus remains flush againstdevice body 12. Pulling of control wires 22 ₂ 22 ₃ deflects effector end20 (grasper shown) in the plane between control wires 22 ₂ 22 ₃. FIG. 3billustrates simultaneous pulling of control wires 22 ₂ 22 ₃. Bothcontrol wires deflect away from device body 12 (at steerable portion 14)and pull effector end 20 in a plane between control wires 22 ₂ 22 ₃resulting in angling of effector end 20.

In the embodiment of FIGS. 3a-b , control wires 22 ₂ 22 ₃ and 22 ₁ areattached directly to device body 12 at B₁ B₂ B₃ and routed into body 12through A₁ A₂ A₃. In FIGS. 4a-b , control wires 22 are attached toretractable levers 26 at a distal end thereof. Levers 26 are disposedwithin slots 28 in device body 12 when device 10 is delivered into thebody. Levers 26 can be spring loaded and sequestered within slots 28during delivery through a port. Once the region of device body 12containing levers 26 exits the port (i.e. is free of the radialconstraints imposed by the port inner wall), levers 26 can spring out;alternatively, levers 26 can fold out when control wires 22 are pulled.In any case, once deployed, levers 26 deflect the distal ends of controlwires 22 away from device body thus increasing leverage of control wires22 and further reducing the pulling force needed to deflect steerableportion 14. When device body 12 is pulled out of the body through aport, levers 26 collapse into slots 28 to facilitate removal through theport.

As is mentioned hereinabove, one embodiments of device body 12 or atleast steerable portion 14 is preferably constructed from a series oflinks. FIGS. 5a-c illustrate one embodiment of links 30 with assembly oflinks 30 into steerable portion 14 illustrated in FIG. 5 d.

Links 30 preferably include several arms 32 (3 shown) mounted around acentral hub 34. As is shown in FIG. 5d , the inter-arm space 36accommodates control wires 22, and thus the number of arms 32(preferably 2-12) dictates the number of control wires 22 used in device10.

Link 30 is preferably fabricated from an alloy or polymer via machiningmolding or the like.

Hub 34 includes a central circular opening 38 (FIG. 5b ), while each arm32 optionally includes an opening 39 (FIG. 5a ). Opening 38 canaccommodate an elongated elastic element (e.g. spring coil 33 shown inFIG. 6 or an elastic tube) for interlinking links 30 and providingdevice body 12 with rigidity and elasticity at steerable portion 12.Openings 39 can be used to route wires for actuating effector end 20 orfor accommodating elastic rods (as an alternative to one central rodmounted through opening 38. Openings 39 can also be used to routeelectrical wires to operate a motor or a camera or jaws of a grasper orany other sensor or actuator at a point distal to steerable portion 14.Opening 38 can also serve as a through lumen for delivering anirrigation tube, optical fibers and the like.

In order to prevent or limit rotation of links 30 when control wires 22are pulled, each link includes tabs 40 and slots 42 on opposite faces.Preferably each arm 32 includes a tab 40 and an opposing slot 42although the length and width can vary between arms 32 of a single link30. Tabs 40 of a link 30 are capable of engaging slots 42 of an adjacentlink 30, thus limiting relative rotation of links 30.

The configuration and positioning of tabs 40 and slots 42 can beselected so as to completely limit rotation, or limit rotation to aspecific angle range (5-15 degrees) or a specific direction etc. In anycase, the engagement between tabs 40 and slots 42 can be reversible thusallowing disengagement therebetween when steerable portion 14 isdeflected and links 30 angle with respect to each other.

FIGS. 7a-h illustrate another embodiment of links 30, which can bestacked as shown in FIGS. 7a-c to form steerable portion 14.

Links 30 of this embodiment of device 10 are roughly disc-shaped andinclude a central opening 50, a plurality of circumferential openings 52(FIGS. 7d-g ), indents 54 (FIGS. 7 e, g, h) and depressions 56 (FIGS.7d, f ).

Central opening 50 serves for routing one or more wires from the devicehandle to effector end 20. Such wires are actuated by the handle tocontrol effector end 20 (e.g. open, close, rotate grasper).Circumferential openings 52 serve for routing control wires 22 foractuating deflection of steerable portion 14. Indents 54 and depressions56 interconnect adjacent links 30 and enable such links to angle withrespect to each other. An elastic rod or tube or spring can bepositioned through central opening 50 to provide elasticity to links 30.

FIG. 8a illustrates an embodiment of device 10 which includes twoindependent steerable portions: 14 and 14′. Device 10 includes a devicebody 12 (also referred to herein as shaft 12) with a typical diameter of5-12 mm. The distal end of device body 12 is fitted with an effector end20 which can be, for example, a grasper as shown in this Figure.Steerable portion 14′ includes a proximal base link 29 which isconnected to the distal end of shaft 12, a series of links 30 and adistal end link 31. Distal ends of control wires 22′_(1,2,3) areconnected to link 31, while the proximal ends of these wires areconnected to a drive unit 24 (FIG. 2) which is operated from the handle.

Control wires 22 _(1,2,3) are connected to distal link 32 of steerableportion 14, and are routed through link 31 and the bodies of links 30′to drive unit 24 (FIG. 2) which is operated from the handle.

FIG. 8b illustrates steerable portions 14 and 14′ in greater details.Each of steerable portions 14 and 14′ includes 9 identical links (30 and30′), however, different number of links of different geometry can beused in each steerable portion. Tabs 40 and slots 42 (describedhereinabove with respect to FIG. 5) of links 30 and 30′ are also shown.

FIG. 8c is a cross sectional view of steerable portions 14 and 14′.Flexible shaft 21 (connected to drive unit 24 at its proximal end) ispositioned through holes 38, 37 of links 29, 30′, 30, 31 and 32, thedistal end of flexible shaft is connected to effector 20.

Control wire 22′₁ passes through hole 28′₁ of link 29 and hole 36′₁ oflink 31; distal end of control wire 22′₁ is connected to link 31 to/inhole 36′₁; control wire 22′₁ is routed out of links 30′. Control wire 22₁ passes through hole 27 ₁ of link 29 and through hole 35 ₁ of links 30′(shown in detail in FIG. 8d ). At link 31, control wire 22 ¹ deflectsout through elongated opening 34 ₁ of link 31 and runs out of links 30to a distal connection point 38 at link 32. Control wires 22′₂ and 22′₃are similar in routing and attachment to control wire 22′₁, whilecontrol wires 22 ₂ and 22 ₃ are similar in routing and attachment ascontrol wire 22 ₁.

FIG. 8d illustrates link 30′ in detail. Central hole 37 accommodatesflexible shaft 21 while holes 35 accommodate control wires 22 _(1,2,3)(tabs 42 and slots 40 are also shown).

FIG. 8e illustrates link 31 in detail. Central hole 38 accommodatesflexible shaft 21 while holes 36 _(1,2,3) serve as connection points forcontrol wires 22′_(1,2,3). Elongated openings 34 _(1,2,3) route controlwires 22 _(1,2,3) out of links 30.

Deflection of portions 14 and 14′ and thus steering and articulation ofshaft 12 is effected via pulling forces on control wires 22 and 22′. Ifa control wire is close to the center of a steerable portion, such asthe case with control wires 22 which run through holes 35 in steerableportion 14′, then a pulling force on these control wires results in arelatively small deflection, in other words the effect of a pullingforce on deflection is in direct relationship to the distance betweencontrol wire 22 to a center of a steerable portion 14. When a controlwire 22 is connected to a distal end of a steerable portion 14 and isfree to move through the proximal base, e.g. when threaded through holes36 _(1,2,3) in link 31, then the effect of a pulling force on steerableportion 14 is enough to deflect it from the longitudinal axis. Thiseffect of the pulling force increases as steerable portion 14 deflectssince control wire 22 bows outward (radially) and the distance betweenthe control wire 22 and center of steerable portion 14 increases.

FIG. 8f illustrates a configuration capable of an 80 degree deflection,i.e. effector end 20 can assume an angle of 100 degrees with respect tothe longitudinal axis of shaft 12. Deflection of proximal steerableportion 14′ is effected by pulling (in a proximal direction) on controlwires 22′_(2,3).

FIG. 8g is a cross sectional view of the device of FIG. 8f showingrouting of control wires 22. A prototype constructed in accordance withthe configuration of FIGS. 8f-g is shown in FIG. 10 b.

FIG. 8h illustrates a configuration capable of an 80 degree deflection,i.e. effector end 20 can assume an angle of 100 degrees with respect tothe longitudinal axis of shaft 12. Deflection of distal steerableportion 14 is effected by pulling (in a proximal direction) on controlwire 22 ₁.

FIG. 8i is a cross sectional view of the device of FIG. 8h showingrouting of control wire 22 ₁. Control wire 22 ₁ runs through hole 35 ₁in links 30′ of steerable portion 14′ and as such its distance from thecenter of steerable portion 14′ is minimal. This small distance, ensuresthat the pulling forces applied on control wire 22 _(1,2,3) will havelittle or no effect on the deflection of steerable portion 14′. At thedistal end of proximal steerable portion 14′, control wire 22 ₁ runsthrough elongated opening 34 ₁ in link 31 and connects to link 32 atpoint 37 ₁. This direct connection positions control wire 22 ₁ outwardfrom the center of steerable portion 14, and therefore increase themoment arm of the pulling force. This enables steerable portion 14′ todeflect (bend) under relatively small pulling forces.

FIG. 8j illustrates routing of control wires 22 ₁ and 22′₁ and centralflexible shaft 21 and the effect of wire routing on deflection forces.In this Figure, “d” represents 1 unit of distance, in this case, thedistance between the center of hole 35 ₁ to the center of link 30′. Thefollowing parameters are used for calculations:

“a”—measurement of the longest arm moment of control wire 22 ₁ from thecenter point of link 30′. La=1.00d;

“b”—measurement of the longest arm moment of control wire 22′₁ from thecenter point of link 30′, Lb=2.75d;

“c”—measurement of the longest arm moment of control wire 22 ₁ from thecenter point of link 30, Lc=4.00d.

A force F22 ₁ is applied to control wire 22 ₁, thus the moment force F22₁ applies on portion 14′ is:

Ma=F22₁ ×La

Ma=F22₁×1.00d

The moment the force F22 ₁ applies on portion 14 is:

Mc=F22₁ ×Le

Mc=F22₁×4.00d

The moment applied by on portion 14 compared to the moment applied onportion 14″ by the same force F22 ₁ is:

Mc/Ma=F22₁×4.00d/F22₁×1.00d=4

The above calculations when applied to commercially available devices,illustrate that the present invention can reduce the wire pulling forceneeded for deflection by at least 25% when compared to such commerciallyavailable devices (see Examples section for further detail).

The bending moment on steerable portion 14 (the “target steerableportion”) caused by force (F22 ₁) applied by control wire 22 ₁ issignificantly greater than the bending moment on steerable portion 14′(the “secondary steerable portion”), and as such, a coupling effectbetween these two steerable portions is minimized.

Minimizing such coupling enables the use of a simple mechanism, such ashand operated mechanism, to steer the articulation without the need toadd a controller to the control wires mechanism.

When using an electro-mechanical mechanism to pull the control wiresthen the moments on the secondary portion may be reduced to zero byusing a controller that is programmed to apply force on control wire22′₁. The magnitude of this force may be calculated by:

Ma=Mb (canceling moments)

Ma=F22₁ ×La=F22₁×1.00d

Mb=F22′₁ ×L=F22′₁×2.35d

F22₁ ×La=F22₁×1.00d=F22′₁ ×L=F22′₁×2.35d

F22′₁ =F22₁×1.00d2.35d

F22′₁=0.42F22₁

As calculated the controller will operate the actuator that pullscontrol wire 22′₁ in a force less than a half of force F22₁(F22′₁=0.42F22 ₁).

It will be appreciated that in cases where an electro-mechanical driveunit is used for pulling the control wires, than the control wiresrouting described above can reduce the energy consumption of the motorscontrolling the first and second steerable portions.

The routing principles described hereinabove may be used in anycombination to deflect two or more steerable portions and generate anyarticulation desired. For example, FIG. 8k illustrates “U”-shapedarticulation with effector end 20 positioned at an angle of 190 degrees.Such articulation is achieved by pulling control wires 22′₁ and 22 ₂.

FIG. 8l illustrates an “S”-shaped articulation which can be achieved bypulling control wires 22′₁ and 22 ₁.

FIGS. 8m-8p illustrate a device having two steerable portions withdeployable arms positioned at a distal end of each steerable portion.Arm 39 p is hingedly connected to link 31 and arm 39 d is hingedlyconnected to link 33. Arms 39 p and 39 d can swing outward and increasethe distance between the end of a control wire connected thereto and thecenter of the deflectable portion. FIG. 8m illustrates arms 39 p and 39d in a folded position, FIG. 8n illustrates arms 39 d and 39 p in anopen position. FIG. 8o illustrates “U”-shaped articulation with arms 39d and 39 p in an open position. FIG. 8p illustrates “S”-shapedarticulation with arms 39 d and 39 p in an open position.

FIG. 8q is a cross sectional view of the present device in a “U”-shapedconfiguration with arms 39 d and 39 p in an open position. In thisexample arms 39 p and 39 d have the same dimensions. The moment arm ofcontrol wire 22 ₁ attached to arm 39 d is 5.5d.

The effect of using arms 39 d and 39 p on the force needed to deflectthe steerable portion can be represented by the following calculation:

Device with no arms:

Mc=F22₁4.00d

Device with arms:

M_(arms) c=F _(arms)22₁×5.50d

M _(arms) c=Mc

F22₁×4.00d=F _(arms)22₁×5.50d

F _(arms)22₁ =F22₁×4.00d/5.50d

F _(arms)22₁ =F22₁×4.00d/5.00d

F _(arms)22₁=0.73F22₁

The foregoing describes examples of device 10 capable of single planearticulation, however it will be appreciated that device 10 having twoor more steerable portions can be deflected to form a multi-planararticulated configuration such as that shown in FIGS. 10d or even acomplete loop. Such multi-planar articulation can be achieved byactuating control wires which are located at different planes or by forexample applying non symmetrical forces on pairs of control wires.

As is mentioned herein above, any handle and mechanism can be used withdevice 10 of the present invention. The construction and operation ofone embodiment of a handle utilizable with the present device isillustrated in FIGS. 1b-h . FIGS. 1b-c illustrate grasper head 20 andsteerable portion 14 which are actuatable via the device handleinterface (18) and its internal mechanism. In this embodiment thesteerable portion is controlled by 4 control wires 22. Steerable portion14 is shown deflected in a direction of pulled control wire 22 ₂.

FIGS. 1d-e and 1g are cross sectional views of device 10 showing themechanism in the handle that enables transfer of interface movements tothe control wires.

Control wires 22 (22 ₁, 22 ₂, 22 ₃, 22 ₄) which are attached to a distalend of steerable portion 14, are routed via a pair of pulleys. Thegrasper jaws are actuated via mechanism 170, to hole 110 a at the baseof spring 110 of housing 500. Control wires 22 are prevented fromslipping through spring 110 by crimp 220. The shape of crimp 220 followsthe shape of the housing of spring 110 to ensure smooth and predictablemovement of a compressed spring 110 when a control wire 22 is pushedaway from center by body 130.

Body 130 is connected to housing 500 by ball joint bearing. Body 130 islocated at the center of the mechanism, and may be tilted with respectto housing 500, by forces applied on interface crown 400 by a user.Control wires 22 surround body 130, when body 130 is in a neutralposition each control wire 22 is pressed against the circumferentialedge of body 130 by slot 90 a of bead 90.

FIG. 1f illustrates the relationship between bead 90, control wire 22(22 ₁ shown) and body 130 in detail. Bead 90 is connected firmly tocontrol wire 22 ₁ and divides control wire 22 into 2 contiguous regions:upper region 22 _(1u) and lower region 22 _(1d). Bead 90 includes a slot90 a that fits into the circumferential edge 130 a of body 130.

FIG. 1h , illustrates in details the control mechanism, shown in atilted position, with control wire 22 ₁ pushed via bead 90 ₁ away fromcenter in order to deflect steerable portion 14. The engagement pointbetween circumferential edge 130 a of body 130 and bead 90 ₁, is at theinner side of slot 90 a. While body 130 pushes bead 90 away from thecenter, opposite-positioned bead 90 ₃ is released from circumferentialedge 130 a. Control wire 22 ₃ is connected at a distal end to anopposite side of control wire 22 ₁. As seen in FIG. 1b , when steerableportion is deflected by control wire 22 ₁, the inner side of portion 14_(in) is shortened, and the length of 14 _(out) at the opposite side ofsteerable portion 14 is increased. The length of wire 22 ₃ must increaseaccordingly. Such length accommodation by control wire 22 ₃ is possibleby compressing spring 110 ₃.

The grasper jaws are actuated via a mechanism (FIGS. 1g-h ) which iscontrollable by the surgeon fingers. When handles 300 are pressed thearms of mechanism 150 elevate piston 240 which closes the jaws. If thesurgeon releases the force applied to handles 3, springs which areconnected to the arms of mechanism 150 push piston 24 back into body 500and the jaws open. Piston 24 is connected to the jaws push/pullmechanism via flexible shaft 17 and tube 16. Flexible shaft 17 and tube16 are also used to transfer rotation and push-pull movement applied onhousing 500. Flexible shaft 17 may be bent without changing its lengthwhich enable bending of portion 17 in centering element 19, withoutresulting an unwanted coupled movement of opening and closing of thejaws i.e. the grasper head and mechanism 150 does not move whilesteerable portion 14 is bent. The dimension of the inner side of body130 is designed not to touch tube 160 when body 130 is tilted to extremepositions.

Although a steerable portion 14 constructed from interconnected links isadvantageous in that it enables modular design, a steerable portion 14constructed from a unitary flexible shaft is also envisaged herein.

A steerable portion constructed from a unitary flexible shaft isadvantageous in that it simplifies construction and manufacturability.In addition, such a shaft is better at insulating central electricalwires, used, for example, in diathermia (monopolar or dipolar).

One example of such an embodiment of steerable portion 14 is shown inFIGS. 9a -b.

Steerable portion 14 can include one or more steerable portions 15(three shown in FIG. 9a ) interposed between guides 17 attached along alength of a flexible shaft 19. Shaft 19 can be made of a tube fabricatedfrom any elastic material including stainless steel, nitinol, rubber,silicon and is typically shaped as a solid or hollow cylinder with adiameter of 5-12 mm with wall thickness 0.1-0.5 mm. Steerable segments15 can be 5-30 mm in length and guides 17 can be dimensioned to displacecontrol wire 22 2-4 mm away from shaft 19. Guides are preferablyconfigured with a central ring 23 for clamping around shaft 19 andseveral (e.g. 2-8) circumferentially attached rings 25 for routing ofcontrol wires 22.

Elasticity of shaft 19 ensures that steerable portion 14 or segment 15deflect when specific control wire or wires 22 are pulled and linearizewhen control wire or wires 22 are released. Shaft 19 is selected so asto enable elastic deflection of one or more steerable portions 14 by 45to 180 degrees.

Another embodiment of a unitary steerable portion 14 is shown in FIGS.9c -i.

This embodiment of unitary steerable portion 14 can be 5 mm in diameter(OD) with a central lumen of at least 1.4 mm. Unitary steerable portion14 is constructed from a polymeric material (e.g. polyamide,polypropylene) that is capable of providing 90 degrees of elasticarticulation (repeatedly) under a pulling force of 10 N (looping,spatial articulation) with a bending radius of about 7 mm. When apulling force is released, an elastic force returns steerable portion 14to a normal, linear configuration.

FIG. 9e illustrates a single unit 67 of unitary steerable portion 14which is designed to allow deflection and yet also stabilizes steerableportion 14 when one or more control wires 22 are pulled.

Each control wire 22 of this configuration of steerable portion 14(three control wires 22 shown, 22 ₁, 22 ₂, 22 ₃) controls deflectionover an arc of 120 degrees. Such a configuration and control wires 22positioning stabilizes steerable portion 14 when all three control wires(22 ₁, 22 ₂, 22 ₃) are pulled.

FIG. 9f illustrates a unitary steerable portion 14 constructed fromseveral contiguous units 67 such as those shown in FIG. 9e . Connector68 functions as a leaf spring-like flexure bar (virtual joint). Theextent of Bending of connector 68 is limited by the geometry of the unit(FIG. 9g ). Thus deflection of one unit with respect to another will beequal to:

$ɛ = {\frac{2}{3} \cdot \frac{I^{2} \cdot \sigma}{H \cdot E}}$

wherein H is the thickness of connector 68, and l is its height. Byincreasing l and decreasing H each pair of adjacent units become moreflexible and less rigid. In such a configuration, the length (L) ofsteerable portion 14 is determined by the bend radius desired and can berepresented by the following: 2πR/4≅L.

FIG. 9h illustrates a configuration wherein connectors 68 are offsetfrom each other along a series of 4 units 67 to enable defection invarious directions. FIG. 9i illustrates a configuration of steerableportion 14 that includes 10 contiguous units 67 with offset connectors68 and a total length of about 11 mm; force 70 is applied to the distalend of such a unified steerable body 14 (simulating wire 22 pull) toillustrate deflection. When such a force is released, connectors 68elastically return steerable portion 14 to a linear (normal)configuration.

In the configuration shown in FIGS. 9e-i , connectors 68 having an 1 of0.5 mm, an H of 0.9 mm and a unit 67 with a diameter of 5 mm, willenable a steerable portion 14 11 mm in length to deflect 90 degreesunder a pulling force of about 10 N.

FIGS. 9j-k illustrate another embodiment of a flexible shaft 70constructed from units 67. Each unit 67 has a top face and a bottom faceeach designed for mating with an opposite face of adjacent unit 67 (i.e.top to bottom and vice versa). As is shown in FIG. 9j , the bottom faceof unit 74 includes two pin engaging elements 77. The top face of unit72 includes a single element 77 for fitting into a space betweenelements 77 of unit 74. When mated, a pin 73 connects elements 77 ofunit 74 and 72 and creates a hinge for allowing articulation. Any numberof units 67 can be pinned together in various orientations (rotationaloffset of hinge region) to create articulation in one of moredirections.

Table 1 below exemplifies two unitary articulating regions constructedaccording to the teachings of the present invention.

TABLE 1 Bending Length Material Diameter Radius Rh Rt Pt Nr A 14 mmPolyamide 5 mm 5 mm 0.4 mm 0.3 mm 1.0 mm 10 (pa12) B 12 mm same 8 mm 8mm 0.5 mm 0.5 mm 0.7 mm 10 Rh—vertical height of segment Rt—verticalthickness of segment ‘body’ Pt—vertical height of articulating unit (twosegments spaced by ‘hinge’) Nr—number of units

FIG. 12 describes an ‘algorithm’ for selecting material properties andunit dimensions based on size and properties of the articulating region.

Device 10 of the present invention can be used in any minimally invasiveprocedure as follows. An access site is created in a tissue wall and theshaft of device 10 is inserted through the access site and positionedtherein using interface 18. If a trocar is used at the access site,device 10 is inserted in a straight configuration. When the effector endof the device is positioned at a target tissue (as ascertained viaimaging), the surgeon operates the device through interface 18 asdescribed hereinabove. Following completion of the procedure, thesurgeon withdraws the device from the body and the access site isclosed.

Steerable portion 14 (constructed from links or as a unitary body) ofthe entire shaft of device 10 can also be fabricated from a transparentmaterial. Use of a transparent material enables visual inspection ofcontrol wires, optical fibers and the like threaded through the devicebody.

FIG. 11a illustrates a steerable portion 14 constructed from transparentlinks 30 (some of the links were removed for the sake of clarity). Opticfibers 62 _(1,2,3) thread through the shaft from the handle to steerableportion 14, through holes 39 of links 30. FIG. 11b is an image of aprototype constructed with transparent links. The transparent steerableportion enables an operator to see control wires 22 _(2,3) and push pullcable 21 through the transparent bodies of links 30.

An illumination source may be connected to the proximal side of opticfibers 62 _(1,2,3) at the handle. When illumination is switched on, thetransparent articulation radiates light out of steerable portion 14. Thelight can be visualized by an operator or an assistant, or may serve asa switch for displaying to the operator data such as CT or MRI data ofthe patient of tissues near the tip of the tool. The light may alsoserve to track the position of the tool or steerable portion 14 thereof.

As used herein the term “about” refers to ±10%.

Additional objects, advantages, and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting.

EXAMPLES

Reference is now made to the following example, which together with theabove descriptions, illustrate the invention in a non limiting fashion.

Force Measurements in Prototype Device

A test was conducted in order to determine the force needed to deflect asteerable portion of a prototype device by 45° and 90° and to measurethe travel length of the wires needed to reach 45° and 90°. Twoprototype devices were constructed. The articulation used to test theforces was as describe in details in FIG. 5. Two types of steerableportions were tested, one constructed from 5 mm diameter links andanother from 8 mm and 5 mm diameter links. Each steerable portionincluded 9 links manufactured by a rapid prototype printer.

Methods

The shaft of the prototype device was fixed to a table and positionedsuch that one of the control wires resided on the top side of the shaft.A force measurement device (Shimpo FGN-5b) was attached to this controlwire and was fixed to a linear rail. In order to measure forces, theforce measurement device was driven away from the shaft until thedesired angle of the articulation was measured. The force was recordedand the travel of device was measured.

Results

Table 2 below summarizes the test results of two prototypes and a priorart Cambridge articulation unit.

As is shown by the results presented in this table, the forces needed todeflect the steerable portion of the present invention were 10% and 15%(present device 5 or 8 mm respectively) of the forces needed to deflecta commercial tool (Cambridge Endo).

Thus, the present device design requires significantly less (6-10 foldsless) force by the operator to deflect the steerable portion. This willenable a surgeon to perform surgery using a manual handle without havingto apply large forces, thus substantially improving operability anddecreasing device-related fatigue. In addition, when used with anelectro-mechanical handle, the present device would not require bulkymotors and batteries but would rather be fully operable using smallmotors and battery packs which would considerably lighten the device andenhance maneuverability thereof.

Another advantage of the present device is shown in FIGS. 10a-c whichdemonstrate the range of articulation and angles of deflection possiblewith the present device. The present device is capable of 2D and 3Darticulation and deflection greater than 180 degrees due to theconfiguration of the links and in particular the unique routing of cabletherein and/or on.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

What is claimed is:
 1. A medical device comprising: (a) an elongateddevice body having a steerable portion including a plurality ofsegments; (b) at least one control wire running alongside said elongateddevice body and being unrestrained at said steerable portion such thattensioning of said at least one control wire angles said steerableportion from a longitudinal axis of said elongated device body anddeflects said at least one control wire away from said steerableportion; and optionally; (c) at least one elongated elastic elementrunning through said plurality of segments and being configured forlimiting rotation of said segments with respect to each other.
 2. Themedical device of claim 1, wherein each of said plurality of segments isconfigured so as to limit rotation thereof with respect to flankingsegments.
 3. The medical device of claim 1, wherein said at least oneelongated elastic element has a rectangular cross section.
 4. Themedical device of claim 1, further comprising an elastic tubular sheathcovering said steerable portion.
 5. The medical device of claim 1,comprising a plurality of control wires, each being for angling saidsteerable portion of said elongated device body in a specific direction.6. The medical device of claim 2, wherein said plurality of segments areinterlinked.
 7. The medical device of claim 1, further comprising atissue manipulator attached to a distal end of said elongated devicebody.
 8. The medical device of claim 7, wherein said tissue manipulatoris a grasper, a tissue cutter, or a needle holder.
 9. The medical deviceof claim 1, further comprising a rigid sheath covering non-steerableportion of said elongated device body.
 10. The medical device of claim1, wherein said elongated elastic element is a spring coil.
 11. Themedical device of claim 2, wherein rotation between adjacent segments ofsaid plurality of segments is limited by tab-slot engagement betweensaid adjacent segments.
 12. The medical device of claim 9, wherein saidcontrol wire is trapped between said device body and said rigid sheathat said non-steerable portion.
 13. The medical device of claim 1,further comprising at least one retractable lever positioned at a distalend of said steerable portion, said at least one retractable lever beingattached to a distal end of said at least one control wire.
 14. Amedical device comprising: (a) an elongated device body having asteerable portion including an elastic shaft; and (b) at least onecontrol wire running alongside said elongated device body and beingunrestrained at said steerable portion such that tensioning of said atleast one control wire angles said steerable portion from a longitudinalaxis of said elongated device body and deflects said at least onecontrol wire away from said steerable portion.
 15. The medical device ofclaim 14, wherein said at least one control wire is routed through apair of guide clamps flanking said steerable portion.